code: def test_transform_search_space_HSS(self) -> None:
      with patch.object(
          self.hss, "flatten", wraps=self.hss.flatten
      ) as mock_hss_flatten:
          flattened_search_space = self.t_hss.transform_search_space(
              search_space=self.hss
          )
          mock_hss_flatten.assert_called_once()
          self.assertIsNot(flattened_search_space, self.hss)
          self.assertFalse(
              isinstance(
                  flattened_search_space, HierarchicalSearchSpace
              )
          )
  
file_path: Ax/ax/modelbridge/transforms/tests/test_cast_transform.py
imports: from copy import deepcopy
  from unittest.mock import patch
  from ax.core.observation import ObservationFeatures
  from ax.core.parameter import ChoiceParameter, FixedParameter, ParameterType, RangeParameter
  from ax.core.search_space import HierarchicalSearchSpace, SearchSpace
  from ax.modelbridge.transforms.cast import Cast
  from ax.utils.common.constants import Keys
  from ax.utils.common.testutils import TestCase
  from ax.utils.testing.core_stubs import get_hierarchical_search_space
label_desc: Use image node_id 5 for calling the CastTransformTest obj's underlying member method code with example usage: obj.test_transform_search_space_HSS() without return types